Tail gas treatment system and method for preparing sodium metabisulfite from active coke desulfurization regeneration gas

Abstract

The application belongs to the technical field of flue gas treatment and discloses a tail gas treatment system and method for preparing sodium metabisulfite from active coke desulfurization regeneration gas, wherein the tail gas treatment system comprises a sodium metabisulfite preparation system, a recycling combustion system, an active coke desulfurization and denitration system and a dust removal unit; the recycling combustion system is connected with a reaction tail gas outlet of the sodium metabisulfite preparation system; the active coke desulfurization and denitration system is provided with a first flue gas inlet, a second flue gas inlet and a regeneration gas outlet, the first flue gas inlet is connected with a flue gas outlet of the recycling combustion system, and the regeneration gas outlet is connected with a gas inlet of the sodium metabisulfite preparation system; and the dust removal unit is connected with a dry tail gas outlet, a dry gas inlet and the second flue gas inlet of the sodium metabisulfite preparation system. The tail gas treatment system and method for preparing sodium metabisulfite from active coke desulfurization regeneration gas have the advantages that sulfur dioxide is not discharged, secondary pollution caused by flue gas discharge does not exist, and the recycling use of sulfur resources can be realized.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of flue gas treatment, and particularly relates to a tail gas treatment system for preparing sodium metabisulfite from active coke desulfurization regeneration gas and a tail gas treatment method for preparing sodium metabisulfite from active coke desulfurization regeneration gas. BACKGROUND

[0002] In the prior art, in the process of preparing sodium metabisulfite from active coke desulfurization and denitrification regeneration gas in steel plants and other related industries, a large amount of reaction tail gas and drying tail gas is generated. These tail gases are usually collected and then absorbed in a tail gas absorption tower using soda solution, and the treated tail gas is directly discharged. Although the SO2 concentration in the tail gas is less than 35 mg / m 3 , secondary pollution is still caused, and equipment investment and chemical agent costs are increased. In addition, the waste heat of the drying tail gas cannot be utilized, resulting in energy waste. SUMMARY

[0003] Therefore, an object of the present application is to provide a tail gas treatment system for preparing sodium metabisulfite from active coke desulfurization regeneration gas. After the drying tail gas of the sodium metabisulfite preparation system is dedusted, part of the drying tail gas is sent to the sodium metabisulfite preparation system for reuse as drying gas, and part of the drying tail gas is sent to the active coke desulfurization and denitrification system together with the reaction tail gas of the sodium metabisulfite preparation system after combustion treatment, and then is used in the sodium metabisulfite preparation system. The entire system does not discharge sulfur dioxide, and secondary pollution caused by flue gas discharge does not exist. In addition, the sulfur resource can be recycled, and energy can be saved.

[0004] Another object of the present application is to provide a tail gas treatment method for preparing sodium metabisulfite from active coke desulfurization regeneration gas.

[0005] To achieve the above object, the present application provides a tail gas treatment system for preparing sodium metabisulfite from active coke desulfurization regeneration gas, which comprises:

[0006] a sodium metabisulfite preparation system;

[0007] a back furnace combustion system, which is connected to a reaction tail gas outlet of the sodium metabisulfite preparation system to send the reaction tail gas discharged from the sodium metabisulfite preparation system to the back furnace combustion system for combustion;

[0008] an active coke desulfurization and denitrification system, which has a first flue gas inlet, a second flue gas inlet and a regeneration gas outlet. The first flue gas inlet is connected to a flue gas outlet of the back furnace combustion system to send the flue gas discharged from the back furnace combustion system to the active coke desulfurization and denitrification system, and the regeneration gas outlet is connected to a gas inlet of the sodium metabisulfite preparation system to send the regeneration gas discharged from the active coke desulfurization and denitrification system to the sodium metabisulfite preparation system.

[0009] A dust removal unit is connected to the dry tail gas outlet of the sodium pyrosulfite preparation system to remove dust from the dry tail gas discharged by the sodium pyrosulfite preparation system, and a flue gas outlet of the dust removal unit is connected to the dry gas inlet of the sodium pyrosulfite preparation system through a first pipeline and connected to the second flue gas inlet through a second pipeline.

[0010] The tail gas treatment system for preparing sodium pyrosulfite by using active coke desulfurization regeneration gas provided by the application can recycle part of the dry tail gas of the sodium pyrosulfite preparation system after dust removal as dry gas, and can send the dry tail gas together with the reaction tail gas of the sodium pyrosulfite preparation system treated by combustion to the active coke desulfurization and denitrification system for treatment, and then recycle the dry tail gas to the sodium pyrosulfite preparation system, so that no sulfur dioxide is discharged outside, no secondary pollution caused by flue gas discharge exists, sulfur resources can be recycled, and energy can be saved.

[0011] Further, the flue gas outlet of the dust removal unit is connected to the first pipeline and the second pipeline through a flue gas main pipe, and an induced draft fan is installed on the flue gas main pipe. In this way, the gas in the dust removal unit after dust removal can be extracted. The temperature of the gas containing sulfur dioxide after dust removal is 100-110 DEG C, and the gas enters the flue gas system, so that the problem of SO2 condensation corrosion can be reduced.

[0012] Further, the tail gas treatment system for preparing sodium pyrosulfite by using active coke desulfurization regeneration gas further comprises a system external flue gas pipeline connected to the gas inlet of the re-furnace combustion system to supply system external flue gas to the re-furnace combustion system. In this way, the composition of the combustion gas in the re-furnace combustion system can be improved, and the external flue gas of the treatment plant can be treated.

[0013] Further, the dust removal unit is one of an inertial dust removal device, a pulse dust removal device, a bag-type dust removal device, an electric dust removal device, a cyclone dust removal device, and an electric-bag dust removal device. The dust removal unit can better remove the particulate matters in the dry tail gas of the sodium pyrosulfite preparation system by selecting the above devices.

[0014] Further, the re-furnace combustion system is a boiler. The re-furnace combustion system can burn the combustible substances such as nitrogen monoxide in the reaction tail gas of the sodium pyrosulfite preparation system by selecting the boiler.

[0015] Further, the tail gas treatment system for preparing sodium pyrosulfite from the active coke desulfurization regeneration gas further comprises a reaction tail gas treatment unit, an inlet of the reaction tail gas treatment unit is communicated with a reaction tail gas outlet of the sodium pyrosulfite preparation system, and an outlet of the reaction tail gas treatment unit is communicated with an inlet of the back-furnace combustion system. Preferably, the reaction tail gas treatment unit is a lye absorption tower. In the present application, the reaction treatment unit is added before the back-furnace combustion system, the processing load of the back-furnace combustion system is reduced, and the reaction tail gas entering the back-furnace combustion system is treated in advance to remove most of the sulfur dioxide in the reaction tail gas.

[0016] Further, the sodium pyrosulfite preparation system comprises a purification system, a synthesis system and a separation and drying system which are communicated in sequence, a gas inlet of the purification system is communicated with the regeneration gas outlet, a liquid inlet of the synthesis system is communicated with the lye preparation system, a reaction tail gas outlet of the synthesis system is communicated with a gas inlet of the back-furnace combustion system, a slurry outlet of the synthesis system is communicated with a slurry inlet of the separation and drying system, a drying gas inlet of the separation and drying system is communicated with a flue gas outlet of the dust removal unit, and a flue gas outlet of the separation and drying system is communicated with a gas inlet of the dust removal unit. In this way, the regeneration gas from the active coke desulfurization and denitrification system is purified by the purification system, reacts with the soda solution in the synthesis system to generate a sodium bisulfite supersaturated solution, and then the sodium bisulfite supersaturated solution enters the separation and drying system for solid-liquid separation and drying to obtain sodium pyrosulfite products. After the drying tail gas is dusted, part of it is used as a drying heat source gas, and the reaction tail gas of the reaction between the regeneration gas and the soda solution is sent to the back-furnace combustion system for combustion treatment.

[0017] Further, the drying gas inlet of the separation and drying system is further communicated with a hot air pipeline. The communication between the drying gas inlet of the separation and drying system and the hot air pipeline can ensure more sufficient drying heat source gas. During use, the drying heat source gas of the separation and drying system is mainly from the hot air from the hot air pipeline, and is supplemented by the dusted gas from the dust removal unit (heat is recovered from the drying tail gas), so that the separation and drying of the sodium bisulfite supersaturated solution generated by the synthesis system can be realized, and finally the finished sodium pyrosulfite is obtained.

[0018] Further, the purification system is a spray washing tower or an oxidation tower. The process water is sprayed to wash the sulfur-rich regeneration gas from the active coke desulfurization and denitrification system to remove HCl and dust in the sulfur-rich regeneration gas. The oxidation tower can oxidize the residual nitrogen monoxide in the sulfur-rich regeneration gas to convert it into nitrogen dioxide, which is then removed by absorption with process water to obtain relatively pure sulfur-rich regeneration gas.

[0019] Further, the synthesis system is a plurality of sodium pyrosulfite synthesis reactors which are connected in series.

[0020] Further, the separation and drying system comprises a centrifuge and a dryer communicated in sequence, a slurry inlet of the centrifuge is communicated with a slurry outlet of the synthesis system, a solid outlet of the centrifuge is communicated with a solid inlet of the dryer, a drying tail gas outlet of the dryer is communicated with a gas inlet of the dust removal unit, and a drying gas inlet of the dryer is communicated with a flue gas outlet of the dust removal unit and the hot air pipeline. In this way, the drying heat source gas of the separation and drying system can mainly use the hot air from the hot air pipeline and the dust-removed gas from the dust removal unit as a supplement, so that the separation product of the sodium bisulfite supersaturated solution generated by the synthesis system is dried, and finally the finished product of sodium pyrosulfite is obtained.

[0021] Further, the active coke desulfurization and denitrification system comprises a flue gas cooling system, an active coke desulfurization and denitrification integrated device and an active coke desorption device communicated in sequence, the flue gas cooling system is connected with a flue gas outlet of the back-furnace combustion system and the second pipeline, so as to cool the flue gas discharged by the back-furnace combustion system and the drying tail gas discharged by the second pipeline into low-temperature flue gas below room temperature, the active coke desulfurization and denitrification integrated device is provided with active coke, which is used for adsorbing and purifying the low-temperature flue gas entering the device, and the active coke desorption device is used for regenerating the saturated active coke discharged from the active coke desulfurization and denitrification integrated device and conveying the generated regeneration gas to the sodium pyrosulfite preparation system through the regeneration gas outlet. In the present application, the working principle of the active coke desulfurization and denitrification system is as follows: the flue gas discharged by the back-furnace combustion system and the drying tail gas of the second pipeline are combined and then enter the flue gas cooling system to be cooled to low-temperature flue gas below room temperature, and then the low-temperature flue gas enters the active coke desulfurization and denitrification integrated device to be adsorbed and purified at low temperature (room temperature or below), and then is directly discharged. When the active coke in the active coke desulfurization and denitrification integrated device is saturated, the active coke is sent to the active coke desorption device to be heated, desorbed and regenerated. The desorption gas from the regeneration gas outlet is sulfur-rich regeneration gas, which can be conveyed back to the sodium pyrosulfite preparation system as a raw material for the synthesis of sodium pyrosulfite. The sulfur-rich regeneration gas obtained by the active coke desulfurization and denitrification system has less gas impurity content, no other particulate matter except dust, and no metal ions such as iron, so that when it is used for the preparation of sodium pyrosulfite, the side reactions are less, the chemical reaction rate is fast, the yield is high, and high-quality (good purity, purity > 98%, no yellowing phenomenon, high whiteness) sodium pyrosulfite can be obtained.

[0022] The present application also provides a tail gas treatment method for preparing sodium pyrosulfite by using active coke desulfurization regeneration gas, which comprises the following steps:

[0023] After the drying tail gas from the sodium pyrosulfite preparation system is dust-removed, part of the drying tail gas is sent to the separation and drying system of the sodium pyrosulfite preparation system as drying heat source gas supplement, and the other part is sent to the active coke desulfurization and denitrification system for desulfurization.

[0024] The reaction tail gas from the sodium pyrosulfite preparation system is sent into the active coke desulfurization and denitrification system after being combusted by the incineration system.

[0025] The sulfur-rich regeneration gas after desulfurization and denitrification by the active coke desulfurization and denitrification system is sent into the sodium pyrosulfite preparation system to prepare sodium pyrosulfite.

[0026] Preferably, the method for active coke desulfurization and denitrification comprises:

[0027] The dry tail gas after dedusting and the synthetic tail gas after incineration are cooled to below room temperature to obtain low-temperature flue gas.

[0028] The low-temperature flue gas is treated by active coke adsorption to remove sulfur dioxide and nitrogen oxides.

[0029] The active coke saturated by adsorption is regenerated to obtain the sulfur-rich regeneration gas. The sulfur-rich regeneration gas obtained by the method for active coke desulfurization and denitrification has less gas impurity content and no other particulate matter except dust and no metal ions such as iron, so that when it is used for sodium pyrosulfite preparation, the side reaction is less, the chemical reaction rate is fast, the yield is high, and high-quality (good purity, purity > 98%, no yellowing phenomenon, and high whiteness) sodium pyrosulfite can be obtained.

[0030] Preferably, the tail gas treatment method for preparing sodium pyrosulfite from active coke desulfurization regeneration gas further comprises: after the dry tail gas is dedusted, the dry tail gas is sent into the flue gas main pipe by an induced draft fan before being sent into the separation and drying system and the active coke desulfurization and denitrification system. In this way, the induced draft fan can extract the gas after dedusting in the dedusting unit, and the temperature of the gas containing sulfur dioxide after dedusting is 100-110℃, which can reduce the problem of SO2 condensation corrosion when the gas enters the flue system.

[0031] Preferably, the tail gas treatment method for preparing sodium pyrosulfite from active coke desulfurization regeneration gas further comprises: after the external source flue gas is combusted by the incineration system, the flue gas is sent into the active coke desulfurization and denitrification system for desulfurization and denitrification. The incineration system can combust and treat combustible substances such as nitrogen monoxide in the reaction tail gas of the sodium pyrosulfite preparation system.

[0032] Preferably, the tail gas treatment method for preparing sodium pyrosulfite from active coke desulfurization regeneration gas further comprises a step of purifying the reaction tail gas before being combusted by the incineration system. The purification method can be to remove HCl and dust in the sulfur-rich regeneration gas by process water spray washing, or to remove residual nitrogen monoxide in the sulfur-rich regeneration gas by ozone oxidation in an oxidation tower, so that the residual nitrogen monoxide is converted into nitrogen dioxide, and then the nitrogen dioxide is removed by process water absorption to obtain relatively pure sulfur-rich regeneration gas.

[0033] Preferably, the temperature of the dry tail gas is 110-129°C. The temperature of the dry tail gas is within the above range, so that it can be used as an auxiliary drying heat source gas to recover heat therefrom, while achieving drying of the separated product of the sodium bisulfite supersaturated solution produced by the synthesis system, and finally obtaining the finished sodium metabisulfite product.

[0034] Additional aspects and advantages of the present application will be in part apparent and in part pointed out below. BRIEF DESCRIPTION OF DRAWINGS

[0035] The above and / or additional aspects and advantages of the present application will become apparent and be readily appreciated from the following description, including the appended drawings.

[0036] Figure 1 is a schematic diagram of a tail gas treatment system for preparing sodium metabisulfite from activated coke desulfurization regeneration gas according to an embodiment of the present application.

[0037] Figure 2 is a schematic diagram of a tail gas treatment system for preparing sodium metabisulfite from activated coke desulfurization regeneration gas according to another embodiment of the present application.

[0038] Figure 3 is a structural diagram of a sodium metabisulfite preparation system, a dust removal unit, and a induced draft fan portion of a tail gas treatment system for preparing sodium metabisulfite from activated coke desulfurization regeneration gas according to an embodiment of the present application.

[0039] Figure 4 is a structural diagram of an adsorption unit of an activated coke desulfurization and denitration system of a tail gas treatment system for preparing sodium metabisulfite from activated coke desulfurization regeneration gas according to an embodiment of the present application.

[0040] REFERENCE NUMERALS:

[0041] 1-sodium metabisulfite preparation system; 101-purification system; 1011-first stage washing tower; 1012-second stage washing tower; 102-synthesis system; 1021-first reactor; 1022-second reactor; 1023-third reactor; 1024-circulating pump; 103-separation and drying system; 1031-centrifuge; 1032-dryer; 1033-blower; 1034-heating device; 1035-first stage cyclone separator; 1036-bag-type dust collector; 104-alkali preparation system; 1041-pure alkali storage bin; 1042-pure alkali slurry tank; 1043-alkali preparation tank; 1044-liquid supplement pump; 105-packaging system; 106-hot air pipeline; 107-pure alkali; 108-finished product; 1081-finished product storage bin; 109-buffer tank; 2-reverberatory combustion system; 3-active coke desulfurization and denitration system; 301-adsorbent particle; 302-air-permeable shell; 4-dust removal unit; 5-induced draft fan; 6-pipeline for flue gas outside the system; 7-treatment unit for reaction tail gas. DETAILED DESCRIPTION

[0042] Embodiments of the present application are described in detail below with reference to the attached drawing figures, wherein the examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the attached drawing figures are exemplary and are intended to explain the present application, and are not to be understood as limiting the present application.

[0043] In the present application, the disclosure of numerical ranges includes all values and further subdivided ranges within the entire range, including the endpoints and subranges given for these ranges.

[0044] In the present application, the raw materials, equipment, etc. involved, if not specifically stated, are raw materials, equipment that can be made by commercial means or known methods; the methods involved, if not specifically stated, can be conventional methods.

[0045] The tail gas treatment system for preparing sodium metabisulfite from active coke desulfurization regeneration gas and the tail gas treatment method for preparing sodium metabisulfite from active coke desulfurization regeneration gas of the embodiments of the present application are described below in conjunction with the accompanying drawings.

[0046] Figure 1 is a schematic diagram of the tail gas treatment system for preparing sodium metabisulfite from active coke desulfurization regeneration gas according to an embodiment of the present application.

[0047] As shown in Figure 1 the tail gas treatment system for preparing sodium metabisulfite from active coke desulfurization regeneration gas of the embodiments of the present application includes a sodium metabisulfite preparation system 1, a reverberatory combustion system 2, an active coke desulfurization and denitration system 3, and a dust removal unit 4.

[0048] The reverberatory combustion system 2 is connected to the reaction tail gas outlet of the sodium metabisulfite preparation system 1 to send the reaction tail gas discharged from the sodium metabisulfite preparation system 1 into the reverberatory combustion system 2 for combustion.

[0049] The active coke desulfurization and denitrification system 3 has a first flue gas inlet, a second flue gas inlet and a regeneration gas outlet, the first flue gas inlet is communicated with the flue gas outlet of the re-burning combustion system 2 to send the flue gas discharged by the re-burning combustion system 2 into the active coke desulfurization and denitrification system 3, and the regeneration gas outlet is communicated with the gas inlet of the sodium bisulfite preparation system 1 to send the regeneration gas discharged by the active coke desulfurization and denitrification system 3 into the sodium bisulfite preparation system 1.

[0050] The dust removal unit 4 is communicated with the dry tail gas outlet of the sodium bisulfite preparation system 1 to remove the dust in the dry tail gas discharged by the sodium bisulfite preparation system 1, and the flue gas outlet of the dust removal unit 4 is communicated with the dry gas inlet of the sodium bisulfite preparation system 11 through the first pipeline and communicated with the second flue gas inlet through the second pipeline.

[0051] The tail gas treatment system for preparing sodium bisulfite by using the regeneration gas of the active coke desulfurization system in the embodiment of the application, after the dry tail gas of the sodium bisulfite preparation system is removed dust, part of the dry tail gas is sent into the sodium bisulfite preparation system as dry gas for reuse, and part of the dry tail gas is sent into the active coke desulfurization and denitrification system together with the combustion-treated reaction tail gas of the sodium bisulfite preparation system for treatment, and then is used in the sodium bisulfite preparation system again, the entire system does not discharge sulfur dioxide, there is no secondary pollution caused by flue gas discharge, the sulfur resource can be recycled, and energy can be saved.

[0052] In some embodiments, the flue gas outlet of the dust removal unit 4 is connected with the first pipeline and the second pipeline through a flue gas main pipe, and an induced draft fan 5 is installed on the flue gas main pipe to extract the gas removed dust in the dust removal unit 4. The temperature of the gas containing sulfur dioxide after dust removal is 100-110℃, which enters the flue gas system, which can reduce the problem of SO2 condensation corrosion.

[0053] In some embodiments, the dust removal unit 4 can be selected from an inertial dust removal device, a pulse dust removal device, a bag type dust removal device, an electric dust removal device, a cyclone dust removal device, an electric-bag dust removal device, etc. As a non-limiting example, the dust removal unit 4 includes but is not limited to one of an inertial dust remover, a pulse dust remover, a bag type dust remover, an electric dust remover, a cyclone dust remover, and an electric-bag composite dust remover, and the dust removal unit is used to remove particulate matters in the dry tail gas of the sodium bisulfite preparation system.

[0054] In some embodiments, the re-burning combustion system 2 can be selected from a boiler to burn the combustible substances such as nitrogen monoxide in the reaction tail gas of the sodium bisulfite preparation system.

[0055] In some embodiments, in order to reduce the processing load of the incineration system, the reaction tail gas entering the incineration system is first treated, and the tail gas treatment system for preparing sodium metabisulfite from the activated coke desulfurization regeneration gas in the embodiments of the present application further comprises a reaction tail gas treatment unit 7, the inlet of the reaction tail gas treatment unit 7 is communicated with the reaction tail gas outlet of the sodium metabisulfite preparation system 1, and the outlet of the reaction tail gas treatment unit 7 is communicated with the inlet of the incineration system 2. As an optional example, the reaction tail gas treatment unit can be an alkali liquor absorption tower. By alkali liquor absorption, most of the sulfur dioxide in the reaction tail gas can be removed.

[0056] In some embodiments, in order to improve the composition of the combustion gas in the incineration system and treat the flue gas outside the plant at the same time, the tail gas treatment system for preparing sodium metabisulfite from the activated coke desulfurization regeneration gas further comprises a system external flue gas pipeline 6, which is communicated with the gas inlet of the incineration system 2 to supply the system external flue gas to the incineration system 2.

[0057] In some embodiments, the sodium metabisulfite preparation system 1 comprises a purification system 101, a synthesis system 102 and a separation and drying system 103 communicated in sequence. Among them, the gas inlet of the purification system 101 is communicated with the regeneration gas outlet, the liquid inlet of the synthesis system 102 is communicated with the alkali preparation system 104, the reaction tail gas outlet of the synthesis system 102 is communicated with the gas inlet of the incineration system 2, the slurry outlet of the synthesis system 102 is communicated with the slurry inlet of the separation and drying system 103, the dry gas inlet of the separation and drying system 103 is communicated with the flue gas outlet of the dust removal unit 4, and the flue gas outlet of the separation and drying system 103 is communicated with the gas inlet of the dust removal unit 4. In this way, the regeneration gas from the activated coke desulfurization and denitrification system is purified by the purification system, and then reacts with the soda solution in the synthesis system to generate sodium bisulfite supersaturated solution. Subsequently, the sodium bisulfite supersaturated solution enters the separation and drying system for solid-liquid separation and drying to obtain sodium metabisulfite product, and part of the dry tail gas after dust removal is used as a dry heat source gas, and the reaction tail gas of the reaction of the regeneration gas and the soda solution is sent to the incineration system for combustion treatment.

[0058] In some embodiments, in order to ensure more sufficient dry heat source gas, the dry gas inlet of the separation and drying system 103 is further communicated with a hot air pipeline 106. In this way, the dry heat source gas of the separation and drying system is mainly from the hot air from the hot air pipeline, supplemented by the gas after dust removal from the dust removal unit, which can realize the drying of the separation product of the sodium bisulfite supersaturated solution generated by the synthesis system, and finally obtain the finished product sodium metabisulfite.

[0059] In some embodiments, in order to better realize the packaging of the finished product sodium pyrosulfite, the sodium pyrosulfite preparation system 1 further comprises a packaging system 105 which is communicated with the solid outlet of the separation and drying system 103. It should be noted here that the packaging system can be a commercially available packaging system or can be only a sodium pyrosulfite collection tank, etc.

[0060] In some embodiments, the purification system 101 can select a spray washing tower to spray process water to wash the sulfur-rich regenerated gas from the active coke desulfurization and denitrification system to remove HCl and dust in the sulfur-rich regenerated gas, etc.

[0061] In other embodiments, the purification system 101 can select an oxidation tower, and the oxidation tower is provided with an ozone inlet, a process water inlet and an acid liquid outlet. The ozone can be prepared by an ozone generator and then used to oxidize the residual nitrogen monoxide in the sulfur-rich regenerated gas to convert it into nitrogen dioxide, which is then removed by process water absorption to obtain relatively pure sulfur-rich regenerated gas.

[0062] In some embodiments, the synthesis system 102 can select multiple-stage sodium pyrosulfite synthesis reactors connected in series with each other, such as commercially available three-stage reactors (for example, three reaction kettles connected in series, and the reaction kettles can be stainless steel reaction kettles, etc.). The sulfur-rich regenerated gas and the soda ash solution configured by the soda ash are reacted in the synthesis system to obtain a sodium bisulfite supersaturated solution, and the sodium bisulfite supersaturated solution is further separated and dried to obtain the finished product sodium pyrosulfite.

[0063] In some embodiments, the separation and drying system 103 comprises a centrifuge and a dryer connected in series, the slurry inlet of the centrifuge is communicated with the slurry outlet of the synthesis system 102, the solid outlet of the centrifuge is communicated with the solid inlet of the dryer, the dry tail gas outlet of the dryer is communicated with the gas inlet of the dust removal unit 4, the drying gas inlet of the dryer is communicated with the flue gas outlet of the dust removal unit 4 and the hot air pipeline 106, and the solid outlet of the dryer is communicated with the inlet of the packaging system 105.

[0064] In some embodiments, the active coke desulfurization and denitrification system 3 is self-contained in a low-temperature oxidation adsorption process (COAP technology) system. The COAP system comprises a flue gas cooling system (such as a spray cooling tower), an active coke desulfurization and denitrification integrated device (such as an adsorption tower, and the adsorbent can be replaced by other adsorbents other than active coke as needed), an active coke desorption device (such as a regeneration tower), etc. connected in series. In use, the flue gas is cooled to low-temperature flue gas by the flue gas cooling system, for example, cooled to below room temperature, preferably below zero Celsius, for example, (-80) ℃ to (-5) ℃, more preferably (-20) ℃ to (-15) ℃, and then the flue gas containing SO2 and NO xThe low-temperature flue gas enters the active coke desulfurization and denitrification integrated device to remove sulfur dioxide and nitrogen oxides, and the adsorbent (e.g., active coke, etc.) saturated with adsorption enters the active coke desorption device (regeneration tower) to heat and desorb sulfur dioxide and nitrogen oxides, forming sulfur-containing regeneration gas (also called sulfur-rich regeneration gas).

[0065] Regarding the temperature selection of the low-temperature flue gas, the inventors found through research that the lower the flue gas temperature, the more beneficial to adsorption purification. However, if the flue gas temperature is too low, the equipment for cooling the flue gas is complex in structure and the energy consumption increases, for example, the cooling equipment, adsorption tower, and pipelines require insulation layers and high sealing requirements, thereby increasing the cost. In addition, too low a temperature condition causes condensate water to easily appear in the adsorption tower, causing the adsorbent to stick and block, affecting adsorption. Therefore, it is beneficial for the flue gas temperature to be cooled to (-20) ℃ to (-15) ℃.

[0066] Specifically, in some embodiments of the present application, the active coke desulfurization and denitrification system 3 includes the flue gas cooling system (e.g., a spray cooling tower, etc.), the active coke desulfurization and denitrification integrated device (e.g., an adsorption tower, etc.), and the active coke desorption device (e.g., a regeneration tower, etc.) sequentially connected in the COAP system described above, wherein the flue gas cooling system has the first flue gas inlet and the second flue gas inlet, and the active coke desorption device has the regeneration gas outlet.

[0067] In some embodiments, the active coke desulfurization and denitrification integrated device is provided with an adsorption unit. As shown in Figure 4 The adsorption unit includes a gas-permeable shell 302 and the adsorbent (e.g., active coke, etc.) filled inside the gas-permeable shell 302, which can be in the form of granular (e.g., adsorbent particles 301 in Figure 4 The adsorbent can also be in the form of an adsorbent body made of powder or granular adsorbent, such as a spherical body or a cylindrical body formed by the powder or granular adsorbent through a binder, etc. Of course, a protective shell can be further formed on the outside of the adsorbent body, such as a gas-permeable membrane covering the outside of the adsorbent body, to improve the strength of the adsorbent body. The gas-permeable shell 302 has gas-permeable holes through which the flue gas can enter the gas-permeable shell. The flue gas can pass through the gaps between adjacent adsorbents and / or the pores of the adsorbents, thereby reducing direct collision, friction and wear between the adsorbents, and dust generation. The gas-permeable shell 302 can be in the form of a rotating body such as a sphere or a cylinder, wherein the diameter of the adsorption unit is 10 mm to 100 mm, and the diameter of the adsorbent is 1 mm to 10 mm.

[0068] More specifically, the flue gas cooling system is connected with the flue gas outlet of the incineration system and the second pipeline to cool the flue gas discharged from the incineration system and the dry tail gas discharged from the second pipeline into low-temperature flue gas, for example, to below room temperature, preferably below 0°C, and more preferably (-20) °C to (-15) °C. The active coke desulfurization and denitrification integrated device is provided with active coke and the like as adsorbents to adsorb and purify the low-temperature flue gas entering the device, and the active coke desorption device is used to regenerate the saturated active coke discharged from the active coke desulfurization and denitrification integrated device and to deliver the generated regeneration gas to the sodium pyrosulfite preparation system through the regeneration gas outlet.

[0069] In the embodiment of the present application, the working principle of the active coke desulfurization and denitrification system is as follows: the flue gas discharged from the incineration system is combined with the dry tail gas of the second pipeline and then enters the flue gas cooling system to be cooled to below room temperature to form low-temperature flue gas, and then the low-temperature flue gas enters the active coke desulfurization and denitrification integrated device at low temperature (room temperature or below room temperature, preferably below 0°C, and more preferably (-20) °C to (-15) °C) to be adsorbed and purified for desulfurization and denitrification, and then is directly discharged. After the active coke in the active coke desulfurization and denitrification integrated device is saturated, it is sent to the active coke desorption device for heating desorption and desorption regeneration. The desorption gas from the regeneration gas outlet is sulfur-rich regeneration gas, which can be delivered back to the sodium pyrosulfite preparation system as a raw material for the synthesis of sodium pyrosulfite. Since the sulfur-rich regeneration gas obtained by using the active coke desulfurization and denitrification system of the embodiment of the present application has a small amount of gas impurities and no other particulate matter except dust and no metal ions such as iron, it can be used for the preparation of sodium pyrosulfite, has few side reactions, fast chemical reaction rate, high yield, and can obtain high-quality (good purity, purity > 98%, no yellowing phenomenon, and high whiteness) sodium pyrosulfite.

[0070] It should be noted that the communication modes between the various constituent devices and components in the tail gas treatment system for preparing sodium pyrosulfite from active coke desulfurization regeneration gas according to the embodiment of the present application include but are not limited to pipeline communication, and any suitable communication mode in the art can be used.

[0071] The tail gas treatment method for preparing sodium pyrosulfite from active coke desulfurization regeneration gas according to the embodiment of the present application is described below. The tail gas treatment method for preparing sodium pyrosulfite from active coke desulfurization regeneration gas according to the embodiment of the present application includes the following steps:

[0072] S101, after the dry tail gas from the sodium pyrosulfite preparation system 1 is dedusted, part of it is sent to the separation and drying system 103 of the sodium pyrosulfite preparation system 1 as dry heat source gas supplement gas, and the other part is sent to the active coke desulfurization and denitrification system 3 for desulfurization.

[0073] In some embodiments, the temperature of the dry tail gas is 110-129°C, including but not limited to 110°C, 115°C, 120°C, 125°C, or 129°C, etc.

[0074] In some embodiments, the composition of the dry tail gas includes: dust 10-30 mg / Nm 3 ; SO2 00-2000 mg / Nm 3 .

[0075] In some embodiments, the temperature of the dedusted gas is 100-110°C, including but not limited to 100°C, 102°C, 105°C, 108°C or 110°C, etc. The composition of the dedusted gas includes: SO2 00-2000 mg / Nm 3 . Since the temperature of the dedusted gas containing sulfur dioxide is 100-110°C, it enters the flue system, which can reduce the problem of SO2 condensation corrosion.

[0076] In some embodiments, the volume ratio of the dedusted dry tail gas sent into the sodium metabisulfite preparation system to the dedusted dry tail gas sent into the active coke desulfurization and denitrification system is appropriate to ensure that the temperature of the dry heat source gas of the separation and drying system of the sodium metabisulfite preparation system is appropriate.

[0077] Generally, the temperature of the dry heat source gas is 120-129°C. If the temperature of the subsequent hot air is lower, more dedusted dry tail gas can be supplemented as the dry heat source gas. If the temperature of the subsequent hot air is higher, less dedusted dry tail gas can be supplemented as the dry heat source gas.

[0078] As an optional example, the volume ratio of the dedusted dry tail gas sent into the sodium metabisulfite preparation system to the dedusted dry tail gas sent into the active coke desulfurization and denitrification system is 1:(3-6), including but not limited to 1:3, 1:4, 1:5 or 1:6, etc.

[0079] S102, the reaction tail gas from the sodium metabisulfite preparation system 1 is sent into the active coke desulfurization and denitrification system 3 for desulfurization and denitrification after being burned by the recycling combustion system 2.

[0080] In some embodiments, the composition of the reaction tail gas includes, by volume fraction: SO2 3-4%, NO 5-7%, N2 48-56%, CO2 5-9%, H2O 24-27%.

[0081] In some embodiments, the tail gas treatment method for preparing sodium metabisulfite by active coke desulfurization regeneration gas further includes the step of purifying the reaction tail gas before being burned by the recycling combustion system.

[0082] As an optional example, the purification of the reaction tail gas adopts alkali absorption method, which can remove most of the sulfur dioxide. As a non-limiting example, the alkali solution can be a 15-30wt% sodium carbonate solution. After the reaction tail gas is absorbed by the alkali solution, the SO2 concentration of the tail gas is 0-10 mg / Nm3 .

[0083] In some embodiments, the incineration system is fueled by natural gas, biogas, liquefied petroleum gas, and coal gas, etc. The composition of the gas after the incineration of the purified reaction tail gas in the incineration system 2 includes, in volume fraction: N2 71.0-72.0%, NO X 4.3-5.3%, CO2 1.6-2.6%, O2 19.64-21.64%.

[0084] It should be noted that the high-temperature combustion of the purified reaction tail gas in the incineration system can remove part of the nitrogen oxides (mainly nitric oxide).

[0085] S103, the sulfur-rich regenerated gas after desulfurization and denitrification in the active coke desulfurization and denitrification system 3 enters the sodium pyrosulfite preparation system 1 to prepare sodium pyrosulfite for sulfur resource recycling.

[0086] It should be noted that, as described above, the active coke desulfurization and denitrification system can be included in the COAP system, including a flue gas cooling system, an active coke desulfurization and denitrification integrated device, and an active coke desorption device, which are sequentially connected. The sulfur-rich regenerated gas here is the desorption gas discharged from the active coke desorption device in the active coke desulfurization and denitrification system (i.e., the gas obtained by desorption of the adsorption-saturated active coke in the active coke desorption device in the active coke desulfurization and denitrification integrated device).

[0087] In some embodiments, the method of active coke desulfurization and denitrification includes the following steps:

[0088] 1) The dust-removed dry tail gas and the incinerated synthetic tail gas are cooled to below room temperature to obtain low-temperature flue gas.

[0089] 2) The low-temperature flue gas is treated by active coke adsorption to remove sulfur dioxide and nitrogen oxides.

[0090] 3) Regeneration of adsorption-saturated active coke to obtain sulfur-rich regenerated gas.

[0091] In some embodiments, the temperature of the low-temperature flue gas is preferably below zero degrees Celsius, for example, (-80) °C to (-5) °C, more preferably (-20) °C to (-15) °C.

[0092] In some embodiments, the composition of the sulfur-rich regenerated gas includes, in volume fraction: SO2 29.0-30.0%, NO 3.13-4.13%, NO2 0.87-1.87%, N2 42.5-43.5%, CO2 3.7-4.7%, H2O 17.8-18.8%.

[0093] In the embodiment of the present application, the sulfur-rich regenerated gas in the sodium metabisulfite preparation system reacts with the lye to obtain a sodium bisulfite supersaturated solution, and finally sodium metabisulfite can be obtained. The specific reaction principle is as follows:

[0094] (1) SO2 is introduced into the sodium carbonate solution until the pH is 4.1 to generate a sodium bisulfite solution, and the reaction formula is as follows:

[0095] Na2CO3+2SO2+H2O→2NaHSO3+CO2;

[0096] (2) Sodium carbonate is added to the sodium bisulfite solution to adjust the pH to 7-8, that is, it is converted into sodium sulfite, and the reaction formula is as follows:

[0097] Na2CO3+2NaHSO3→2Na2SO3+CO2+H2O;

[0098] (3) Sodium sulfite reacts with SO2 again to generate a sodium bisulfite solution with a pH of 4.1. The reaction formula is as follows:

[0099] Na2SO3+SO2+H2O→2NaHSO3;

[0100] (4) When the content of sodium bisulfite in the solution reaches the supersaturation concentration, sodium metabisulfite crystals are precipitated, and the reaction formula is as follows:

[0101] 2NaHSO3→Na2S2O5+H2O;

[0102] The total reaction equation is: Na2CO3+2SO2→Na2S2O5+CO2.

[0103] As an optional example, the process for preparing sodium metabisulfite is as follows: first, soda ash 107 is configured into a 15-30wt% soda ash solution in the lye preparation system 104, then the purified sulfur-rich regenerated gas is reacted with the soda ash solution in the synthesis system 102 to generate a sodium bisulfite supersaturated solution, and then the sodium bisulfite supersaturated solution is subjected to centrifugal separation and drying to obtain sodium metabisulfite crystal finished product 108.

[0104] In some embodiments, the purification of the sulfur-rich regenerated gas is carried out in the purification system 101. The purification method can choose to remove HCl and dust in the sulfur-rich regenerated gas by process water spray washing, or can choose to remove residual nitrogen monoxide in the sulfur-rich regenerated gas by ozone oxidation in the oxidation tower, so that the residual nitrogen monoxide is converted into nitrogen dioxide, and then the nitrogen dioxide is removed by process water absorption to obtain relatively pure sulfur-rich regenerated gas.

[0105] In some embodiments, the tail gas treatment method of the active coke desulfurization regenerated gas for preparing sodium metabisulfite further comprises: after the dry tail gas is dedusted, it is sent into the flue gas main pipe by the induced draft fan 5 before being sent into the separation and drying system 103 and the active coke desulfurization and denitrification system 3.

[0106] In some embodiments, the tail gas treatment method for preparing sodium metabisulfite by active coke desulfurization regeneration gas further comprises: sending the external flue gas into the active coke desulfurization and denitrification system 3 after being combusted by the reverberatory combustion system 2.

[0107] As an optional example, the external flue gas composition includes, in volume fraction: O2 5.89-6.89%, N2 72.48-73.48%, CO2 12.4-13.4%, SO2 0.05-0.25%, NO X 0.007-0.038%, H2O 7.08-8.08%; wherein the content of SO2 and NO X in each cubic meter of external flue gas is: SO2 3500-4500 mg / m 3 , NO X 500-700 mg / m 3 . At this time, the flue gas composition discharged by the reverberatory combustion system 2 includes, in volume fraction: N2 71.0-72.0%, NO X 4.3-5.3%, CO2 1.6-2.6%, O2 19.64-21.64%, SO2 0.0005-0.0009%. Here, the external flue gas can be off-site flue gas, etc.

[0108] The tail gas treatment method for preparing sodium metabisulfite by active coke desulfurization regeneration gas of the embodiment of the present application directly or after purification, the reaction tail gas from the sodium metabisulfite preparation system enters the reverberatory combustion system for high-temperature combustion, then part of the dry tail gas is combined and enters the active coke desulfurization and denitrification system, and finally the sulfur-rich regeneration gas generated by the active coke desulfurization and denitrification system is reused to the sodium metabisulfite preparation system. The whole process can make sulfur dioxide not be discharged, and always be in the system circulation, and further, there is no secondary pollution caused by flue gas discharge.

[0109] The tail gas treatment system for preparing sodium metabisulfite by active coke desulfurization regeneration gas, the tail gas treatment method for preparing sodium metabisulfite by active coke desulfurization regeneration gas and some features of the present application are further described in the following non-limiting embodiments.

[0110] As shown in Figure 2 , the tail gas treatment system for preparing sodium metabisulfite by active coke desulfurization regeneration gas of the embodiment comprises a sodium metabisulfite preparation system 1, a reverberatory combustion system 2, an active coke desulfurization and denitrification system 3, a dust removal unit 4 and a reaction tail gas treatment unit 7.

[0111] As shown in Figure 3 , the sodium metabisulfite preparation system 1 comprises a purification system 101, a synthesis system 102 and a separation and drying system 103 which are sequentially communicated.

[0112] The purification system 101 is a spray washing tower, which comprises a first-stage washing tower 1011 and a second-stage washing tower 1012 connected in series. The flue gas outlet of the purification system 101 is connected to the gas inlet of the synthesis system 102. The synthesis system 102 is a three-stage reactor (three stainless steel reactors connected in series, i.e., a first reactor 1021, a second reactor 1022, and a third reactor 1023), and each reactor is connected to a circulating pump 1024 for circulating the reaction solution.

[0113] The liquid inlet of the synthesis system 102 is connected to the alkali preparation system 104. The alkali preparation system 104 is a full-automatic alkali preparation system, which prepares the soda ash 107 into an alkali solution with a concentration of 15-30 wt%. The full-automatic alkali preparation system comprises a soda ash storage 1041 for providing the soda ash, a soda ash slurry tank 1042 for preparing the soda ash slurry, an alkali preparation tank 1043 for preparing the soda ash solution, and a make-up pump 1044 for outputting the soda ash solution in the alkali preparation tank 1043. The slurry outlet of the synthesis system 102 is connected to the slurry inlet of the separation and drying system 103.

[0114] The separation and drying system 103 comprises a centrifuge 1031 and a drying machine 1032 connected in series. The slurry inlet of the centrifuge 1031 is connected to the slurry outlet of the synthesis system 102 via a buffer tank 109, and the liquid outlet of the centrifuge 1031 is connected to the alkali preparation tank 1043 via the buffer tank 109. The solid outlet of the centrifuge 1031 is connected to the solid inlet of the drying machine 1032. The drying gas inlet of the drying machine 1032 is connected to the hot air pipeline 106. The hot air is obtained by heating the cold air input by the air blower 1033 by a heating device 1034, which can be a steam heat exchanger or an electric heater. The solid outlet of the drying machine 1032 is connected to the inlet of the packaging system 105 via a first-stage cyclone separator 1035 and a finished product storage 1081. The packaging system 105 is a ton bag packaging machine. The finished product storage 1081 and the packaging system 105 are both connected to a bag-type dust collector 1036 for dust removal during the collection of the finished product. The solid outlet of the bag-type dust collector 1036 is connected to the finished product storage 1081 to collect the residual sodium pyrosulfite product after dust removal.

[0115] The reaction tail gas treatment unit 7 is an alkali solution absorption tower, which uses a 20 wt% soda ash solution as the alkali solution. The inlet of the reaction tail gas treatment unit 7 is connected to the reaction tail gas outlet of the synthesis system 102 in the sodium pyrosulfite preparation system 1, so as to absorb the reaction tail gas by the alkali solution and remove most of the sulfur dioxide.

[0116] The recycling combustion system 2 is a steam boiler, which uses natural gas as fuel. The gas inlet of the recycling combustion system 2 is connected to the outlet of the reaction tail gas treatment unit 7 and the flue gas pipeline 6 outside the system, so as to burn the reaction tail gas after alkali absorption and the flue gas outside the system together.

[0117] The dust removal unit 4 is a bag filter, and the gas inlet of the dust removal unit 4 is connected to the dry tail gas outlet of the dryer in the separation and drying system 103 through a first cyclone separator 1035 to remove dust from the dry tail gas discharged from the separation and drying system 103 in the sodium pyrosulfite preparation system. The solid outlet of the dust removal unit 4 is connected to the finished product bin 1081. The flue gas outlet of the dust removal unit 4 is connected to the inlet of the first pipeline and the inlet of the second pipeline, the outlet of the first pipeline is connected to the drying gas inlet of the dryer in the separation and drying system 103, and the outlet of the second pipeline is connected to the active coke desulfurization and denitrification system 3.

[0118] The active coke desulfurization and denitrification system 3 is provided in the COAP system and includes a flue gas cooling system, an active coke desulfurization and denitrification integrated device, an active coke desorption device, and the like connected in sequence. The flue gas cooling system adopts a spray cooling tower, the active coke desulfurization and denitrification integrated device adopts an adsorption tower, the adsorbent is active coke, and the active coke desorption device adopts a regeneration tower. The flue gas cooling system of the active coke desulfurization and denitrification system 3 has a first flue gas inlet and a second flue gas inlet, and the active coke desorption device has a regeneration gas outlet. The first flue gas inlet is connected to the flue gas outlet of the furnace combustion system 2, the second flue gas inlet is connected to the outlet of the second pipeline, and the regeneration gas outlet is connected to the gas inlet of the purification system 101 in the sodium pyrosulfite preparation system 1.

[0119] The tail gas treatment method for preparing sodium pyrosulfite by using the active coke desulfurization regeneration gas in the embodiment includes the following steps:

[0120] (1) The dry tail gas with a temperature of 110-120℃ from the sodium pyrosulfite preparation system 1 is sent to the dust removal unit 4, and after removing the particulate matter, it is sent to the flue gas main pipe through the induced draft fan 5. Then, 1 / 4 of the dry tail gas is sent to the separation and drying system in the sodium pyrosulfite preparation system 1 as a complementary gas for the dry heat source gas (125℃) from the hot air pipeline 106, and 3 / 4 of the dry tail gas enters the active coke desulfurization and denitrification system 3 to be desulfurized.

[0121] The composition of the dry tail gas is: dust 20 mg / Nm 3 , SO2 500 mg / Nm 3 ; and the temperature of the dry gas after removing the particulate matter by the dust removal unit is 100-110℃, and the composition is: SO2 500 mg / Nm 3 .

[0122] (2) The reaction tail gas with a temperature of 70℃ from the sodium pyrosulfite preparation system 1 is sent to the furnace combustion system 2 after being purified by absorbing the 20wt% pure alkali solution, and then the reaction tail gas is sent to the active coke desulfurization and denitrification system 3 after being combusted by the furnace combustion system 2 together with the off-site flue gas from the flue gas pipeline 6 outside the system.

[0123] The composition of the reaction tail gas is: SO2 4%, NO 7%, N2 54%, CO2 8%, H2O 27% by volume fraction; the composition of the off-site flue gas is: O2 6.39%, N2 72.96%, CO2 12.9%, SO2 0.15%, NO X 600mg / m 3 3%; H2O 7.58%; SO2 4000mg / m X 3; NO 3 600mg / m X 3; the main components of the flue gas discharged by the recycling combustion system 2 include: N2 71.5%, NO 3 4.8%, CO2 2.1%, O2 21.14% by volume fraction.

[0124] (3) The sulfur-rich regenerated gas generated by the activated coke desulfurization and denitrification system 3 is introduced into the sodium pyrosulfite preparation system 1 to prepare sodium pyrosulfite, so as to recycle and utilize sulfur resources.

[0125] The method for desulfurization and denitrification of activated coke includes the following steps:

[0126] 1) The dust-removed dry tail gas and the recycling combustion synthetic tail gas are introduced into a flue gas cooling system to be cooled to below room temperature (for example, -20°C) to obtain low-temperature flue gas;

[0127] 2) The low-temperature flue gas is treated by activated coke adsorption to remove sulfur dioxide and nitrogen oxides;

[0128] 3) The saturated activated coke is regenerated to obtain sulfur-rich regenerated gas.

[0129] The composition of the sulfur-rich regenerated gas is: SO2: 29.5%, NO: 3.6%, NO2 1.4%, N2: 43%, CO2: 4.2%, H2O: 18.3%.

[0130] The process for preparing sodium pyrosulfite by using the sulfur-rich regenerated gas is: first, soda ash 107 is configured into a 20wt% soda ash solution in an alkali preparation system 104, then the sulfur-rich regenerated gas (flow rate is 2500Nm 3 / h) purified by process water spray washing is reacted with the soda ash solution (flow rate is 6.3m 3 / h) at 55-75°C in a synthesis system 102 for 40min to generate a sodium bisulfite supersaturated solution, and then the sodium bisulfite supersaturated solution is centrifuged and dried at 115°C to obtain sodium pyrosulfite crystalline finished product 108.

[0131] In summary, the tail gas treatment system and method for preparing sodium metabisulfite from active coke desulfurization regeneration gas in the embodiment of the present application, after the dry tail gas is dedusted, part of the dry tail gas enters the active coke desulfurization and denitration system, and part of the dry tail gas enters the sodium metabisulfite preparation system as a supplementary gas for the drying heat source gas; at the same time, the reaction tail gas enters the back-furnace combustion system, and after the combustion forms flue gas, the flue gas enters the active coke desulfurization and denitration system, and finally the sulfur-rich regeneration gas generated by the active coke desulfurization and denitration system is recycled to the sodium metabisulfite preparation process. In the whole process, there is no tail gas absorption tower, no secondary sulfur pollution caused by flue gas discharge, the recycling of sulfur resources can be realized, and the cost is low.

[0132] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0133] In addition, the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, for example, two, three, etc., unless otherwise specifically limited.

[0134] In the present application, unless otherwise specifically defined and limited, the terms "mounting", "connection", "connection", "fixing" and the like should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected or in communication with each other; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication or interaction relationship of two elements, unless otherwise specifically limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0135] In the present application, unless specifically stated and limited otherwise, a first feature "on" or "under" a second feature can be directly in contact with the second feature, or indirectly in contact with the second feature through an intermediate medium. Also, a first feature "over", "above" and "on top of" a second feature can be directly above or obliquely above the second feature, or simply means that the first feature is horizontally higher than the second feature. A first feature "under", "below" and "underneath" a second feature can be directly below or obliquely below the second feature, or simply means that the first feature is horizontally lower than the second feature.

[0136] In the present application, the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" mean that a particular feature, structure, material or characteristic is included in at least one embodiment or example of the present application. Exemplary representations of the above terms in the present specification are not necessarily directed to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics can be combined in any suitable manner in one or more embodiments or examples. In addition, different embodiments or examples described in the present specification and features of different embodiments or examples can be combined and combined by those skilled in the art without contradiction.

[0137] Although the embodiments of the present application have been shown and described above, it is understood that the above-described embodiments are exemplary, and should not be construed as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above-described embodiments within the scope of the present application.

Claims

1. An off-gas treatment system for producing sodium metabisulfite from activated coke desulfurization regeneration gas, characterized by, The system comprises: a sodium metabisulfite preparation system; a re-burning system connected to an exhaust gas outlet of the sodium metabisulfite preparation system to burn exhaust gas discharged from the sodium metabisulfite preparation system; an active coke desulfurization and denitrification system having a first flue gas inlet connected to a flue gas outlet of the re-burning system to send flue gas discharged from the re-burning system into the active coke desulfurization and denitrification system, and a regeneration gas outlet connected to a gas inlet of the sodium metabisulfite preparation system to send regeneration gas discharged from the active coke desulfurization and denitrification system into the sodium metabisulfite preparation system; a dust removal unit connected to a dry gas outlet of the sodium metabisulfite preparation system to remove dust from dry gas discharged from the sodium metabisulfite preparation system, and having a flue gas outlet connected to a dry gas inlet of the sodium metabisulfite preparation system through a first pipeline and connected to the second flue gas inlet through a second pipeline.

2. The tail gas treatment system for producing sodium metabisulfite from activated coke desulfurization regeneration gas according to claim 1, characterized in that, The flue gas outlet of the dust removal unit is connected to the first pipeline and the second pipeline through a flue gas main pipe, and an induced draft fan is installed on the flue gas main pipe.

3. The tail gas treatment system for producing sodium metabisulfite from activated coke desulfurization regeneration gas according to claim 1, characterized in that, The system further comprises an external flue gas pipeline connected to a gas inlet of the re-burning system to supply external flue gas to the re-burning system.

4. The tail gas treatment system for producing sodium metabisulfite from activated coke desulfurization regeneration gas according to claim 1, characterized by, The dust removal unit is one of an inertial dust removal device, a pulse dust removal device, a bag-type dust removal device, an electric dust removal device, a cyclone dust removal device, and an electric-bag dust removal device. The re-burning system is a boiler.

5. The tail gas treatment system for producing sodium metabisulfite from activated coke desulfurization regeneration gas according to claim 1, characterized in that, The sodium metabisulfite preparation system comprises a purification system, a synthesis system, and a separation and drying system connected in sequence, a gas inlet of the purification system is connected to the regeneration gas outlet, a liquid inlet of the synthesis system is connected to an alkali preparation system, a reaction exhaust gas outlet of the synthesis system is connected to a gas inlet of the re-burning system, a slurry outlet of the synthesis system is connected to a slurry inlet of the separation and drying system, a dry gas inlet of the separation and drying system is connected to a flue gas outlet of the dust removal unit, and a flue gas outlet of the separation and drying system is connected to a gas inlet of the dust removal unit. The reaction exhaust gas treatment unit is an alkali liquor absorption tower.

6. The tail gas treatment system for producing sodium metabisulfite from activated coke desulfurization regeneration gas according to claim 5, characterized by, The purification system is a spray washing tower or an oxidation tower. The synthesis system comprises multiple sodium metabisulfite synthesis reactors connected in series.

7. The tail gas treatment system for producing sodium metabisulfite from activated coke desulfurization regeneration gas according to claim 6, characterized by, The sodium metabisulfite preparation system comprises a purification system, a synthesis system, and a separation and drying system connected in sequence, a gas inlet of the purification system is connected to the regeneration gas outlet, a liquid inlet of the synthesis system is connected to an alkali preparation system, a reaction exhaust gas outlet of the synthesis system is connected to a gas inlet of the re-burning system, a slurry outlet of the synthesis system is connected to a slurry inlet of the separation and drying system, a dry gas inlet of the separation and drying system is connected to a flue gas outlet of the dust removal unit, and a flue gas outlet of the separation and drying system is connected to a gas inlet of the dust removal unit. The reaction exhaust gas treatment unit is an alkali liquor absorption tower. The purification system is a spray washing tower or an oxidation tower. The synthesis system comprises multiple sodium metabisulfite synthesis reactors connected in series. And / or, the separation and drying system comprises a centrifuge and a dryer connected in sequence, the slurry inlet of the centrifuge is connected with the slurry outlet of the synthesis system, the solid outlet of the centrifuge is connected with the solid inlet of the dryer, the dry tail gas outlet of the dryer is connected with the gas inlet of the dust removal unit, the drying gas inlet of the dryer is connected with the flue gas outlet of the dust removal unit and the hot air pipeline.

8. The tail gas treatment system for the production of sodium metabisulfite from activated coke desulfurization regeneration gas according to any one of claims 1-7, characterized in that, The active coke desulfurization and denitrification system comprises a flue gas cooling system, an active coke desulfurization and denitrification integrated device and an active coke desorption device connected in sequence, the flue gas cooling system is connected with the flue gas outlet of the recycling combustion system and the second pipeline to cool the flue gas discharged by the recycling combustion system and the dry tail gas discharged by the second pipeline into low-temperature flue gas below room temperature, the active coke desulfurization and denitrification integrated device is provided with active coke therein for adsorbing and purifying the low-temperature flue gas entering therein, and the active coke desorption device is used for regenerating the saturated active coke discharged from the active coke desulfurization and denitrification integrated device and conveying the generated regeneration gas to the sodium pyrosulfite preparation system through the regeneration gas outlet.

9. A tail gas treatment method of active coke desulfurization regeneration gas for producing sodium metabisulfite, characterized by, It comprises: After the dry tail gas from the sodium pyrosulfite preparation system is dusted, part of it is sent to the separation and drying system of the sodium pyrosulfite preparation system as dry heat source gas supplement, and the other part is sent to the active coke desulfurization and denitrification system for desulfurization; After the reaction tail gas from the sodium pyrosulfite preparation system is combusted by the recycling combustion system, it is sent to the active coke desulfurization and denitrification system for desulfurization and denitrification; The sulfur-rich regeneration gas after desulfurization and denitrification by the active coke desulfurization and denitrification system enters the sodium pyrosulfite preparation system to prepare sodium pyrosulfite.

10. The tail gas treatment method of producing sodium metabisulfite from activated coke desulfurization regeneration gas according to claim 9, characterized by, The method for active coke desulfurization and denitrification comprises: The dusted dry tail gas and the recycled synthetic tail gas are cooled to below room temperature to obtain low-temperature flue gas; The low-temperature flue gas is treated by active coke adsorption to remove sulfur dioxide and nitrogen oxides; The adsorption-saturated active coke is regenerated to obtain the sulfur-rich regeneration gas; And / or, the tail gas treatment method for preparing sodium pyrosulfite by using the active coke desulfurization regeneration gas further comprises that the dry tail gas after being dusted is sent to the main flue gas pipe by an induced draft fan before being sent to the separation and drying system and the active coke desulfurization and denitrification system; And / or, the tail gas treatment method for preparing sodium pyrosulfite by using the active coke desulfurization regeneration gas further comprises that the external flue gas is combusted by the recycling combustion system and then sent to the active coke desulfurization and denitrification system for desulfurization and denitrification; And / or, the tail gas treatment method for preparing sodium pyrosulfite by using the active coke desulfurization regeneration gas further comprises a step of purifying the reaction tail gas before being combusted by the recycling combustion system; And / or, the temperature of the dry tail gas is 110-129℃.

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